In a system for driving a railway vehicle (a railway vehicle driving system), a plurality of electric motors (alternating-current electric motors) are operated in parallel using one or a plurality of inverter devices.
To detect abnormalities of a plurality of electric motors, an electric motor parallel operation system disclosed in Patent Literature 1, which is not a technology applied to the railway vehicle driving system, always grasps a differential current among the electric motors and, when the differential current is equal to or larger than a setting value, determines that some abnormality has occurred and generates an abnormality signal.